FORMATION OF INSULATING FORSTERITE FILM ON GRAIN-ORIENTED SILICON STEEL SHEET

• Main Authors: SUGA YOUZOU, KONNO TOYOHIKO
• Format: Patent
• Language: English
• Published: 07.10.1985
• Subjects: ALLOYS; CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PURPOSE:To increase the adhesive strength and tension applied to a silicon steel sheet and to improve the magnetic characteristics by forming sub-scale on the surface of the steel sheet contg. prescribed amounts of S, Se and Mn and by subjecting the steel sheet to finish annealing in an atmosphere under a prescribed partial pressure of oxygen. CONSTITUTION:A silicon steel contg. <=0.01wt% S+0.405Se and 0.05+7(S+ 0.405Se)-0.8wt% man is cold rolled to the final thickness. The resulting silicon steel strip is decarburized to form sub-scale contg. SiO2 on the surface of the steel strip. The steel strip is then coated with an MgO-base protective coating material for annealing, and it is held at 850-1,100 deg.C annealing temp. under a partial pressure (PH2O/PH2) of oxygen in the range defined by points A, B, C, D, E in the diagram.